1. Field of the Invention
The invention relates to an aqueous liquid bleaching composition comprising a selected water-insoluble organic peroxy acid, which composition may be used for the bleaching of fabrics and hard surfaces.
2. The Prior Art
Quite a number of organic peroxy acids have been reported in the literature. These peroxy materials have begun to assume great commercial importance as bleaches, especially for fabrics. Many of the more effective organic peroxy acids are solid, substantially water-insoluble materials. Much of the published art has been directed at devising means for stably suspending these acids in water.
One of the early patents in the area is U.S. Pat. No. 3,996,152 (Edwards et al.) disclosing the suspension of diperoxyacids by non-starch thickening agents such as Carbopol 940.RTM. in an aqueous media at low pH. Suggested as suitable actives were diperazelaic, diperbrassylic, dipersebacic and diperisophthalic acids. U.S. Pat. No. 4,017,412 (Bradley) reports similar systems except that starch based thickening agents were employed. From later investigations it became evident that the thickener types mentioned in the foregoing patents formed gel-like matrices which exhibited instability upon storage at elevated temperatures. When formulated at high levels, these thickeners became more stable but then caused difficulties with pourability.
U.S. Pat. No. 4,642,198 (Humphreys et al.) lists an even more expansive variety of water-insoluble organic peroxy acids intended for suspension in an aqueous, low pH liquid. Herein was first disclosed the use of surfactants, both anionic and nonionic, as suspending agents for the peroxy acid particles. The preferred peroxy material was identified as 1,12-diperoxydodecanedioic acid (DPDA) and this was employed in almost all the examples.
EP No. 0 176 124 (DeJong et al.) also focuses upon surfactant suspended 1,12-diperoxydodecanedioic acid in a low pH aqueous liquid. This art informs that surfactants other than alkylbenzene sulfonate have a detrimental effect upon chemical stability of the suspensions.
EP No. 0 240 481 (Boyer et al.) seemingly also finds some special significance in the use of alkylbenzene sulfonate, focuses upon DPDA, and further suggests use of magnesium sulfate as a suspension aid.
U.S. Pat. No. 4,655,781 (Hsieh et al.) is concerned with structuring of surface active peroxy acids in substantially nonaqueous media. Of primary interest and illustrated in the examples are alkyl monoperoxysuccinic acid and monocarboxylic fatty peracids.
The aforementioned art has placed great emphasis upon optimizing the suspending or thickening chemical components of the liquid bleach to improve stability. Evidently, there has been little consideration given to examining the peroxy acid itself as a means to improving suspension properties.
Furthermore, while the use of surfactants and electrolytes have provided a certain measure of chemical and physical stability, this stability is only evident at lower temperatures. At slightly elevated temperatures, instability problems still remain.
Consequently, it is an object of the present invention to provide an improved aqueous liquid bleach composition based upon a solid, substantially water-insoluble organic peroxy acid wherein the above drawbacks are mitigated.
More specifically, it is an object of the present invention to provide an aqueous suspension of a solid, substantially water-insoluble organic peroxy acid which is chemically and physically stable throughout a wide range of temperatures.
These and other objects of the present invention will become apparent as further details are provided in the subsequent discussion and Examples.